如何知道Linux中的执行时间 [英] How to know the execution time in linux

问题描述

假设我要在名为launcher.sh的脚本中启动三个脚本(a.sh b.sh c.sh):

Suppose that I have three script(a.sh b.sh c.sh) to be launched in a script called launcher.sh:

first=`date +%s`

./a.sh &
./b.sh &
./c.sh &

final=`date +%s`

executionTime=`echo "scale=3;($final - $first)/3600" | bc`

echo $executionTime

我知道上面的脚本不起作用，因为launcher.sh将在启动a.sh，b.sh和c.sh之后立即完成.在没有&" 的情况下启动a.sh，b.sh和c.sh浪费了时间，因为它们不必彼此等待.

I know above script won't work because launcher.sh will finish immediately after launching a.sh, b.sh and c.sh. Launching a.sh, b.sh and c.sh without "&" is wasting time because they don't have to wait for each other.

假设它们的执行时间分别为5秒，10秒和7秒，那么我如何才能获得10秒的总执行时间呢?

Suppose that the execution time for them are 5 seconds, 10 seconds and 7 second respectively, how can I get 10 seconds as the overall execution time?

推荐答案

使用wait:

first=`date +%s`

./a.sh &
./b.sh &
./c.sh &

wait

...

引用help wait:

wait: wait [id]

Wait for job completion and return exit status.

Waits for the process identified by ID, which may be a process ID or a
job specification, and reports its termination status.  If ID is not
given, waits for all currently active child processes, and the return
status is zero.  If ID is a a job specification, waits for all processes
in the job's pipeline.

Exit Status:
Returns the status of ID; fails if ID is invalid or an invalid option is
given.

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